The invention relates to an automatic machining system, and particularly to an automatic machining system which accomplishes scribing, punching and drilling in production of machine parts at instructions given from an operating unit, based on indications on a display unit.
Whereas scribing, punching and drilling take place in the preparatory and finishing stages of machining, scribing and punching are usually accomplished by hand, and drilling, with a manually operated drilling machine. Although numerically controlled (NC) drilling machines have also become available over the recent years, manually operated drilling machines have been predominantly used except in achieving particularly complex operations or in working on pieces which require many drilling operations.
However, manually operated drilling machines have shortcomings such as inability to achieve accurate positioning and need for separate positioning operations even in repeated drilling in the same position. The predominant use, as stated above, of manually operated drilling machines in spite of these disadvantages is attributable to the circumstances described below, in addition to the large cost of NC drilling machines.
The usual procedure of giving an operating instruction to an NC system is for the operator or programmer to prepare a punched (paper) tape in accordance with the machining sequence, and have the machine tool read the so prepared paper tape to receive the instruction and machine the workpiece accordingly. However, when a small number of workpieces are to be machined, the intervention of the paper tape results in inconveniences such as the time required for preparation of the tape being longer than the time required for actual machining and the troubles of storing paper tapes and choosing the desired from the group of tapers. Moreover, when a conventional NC drilling machine is used for drilling operations, every time the distance between the drill and the workpiece varies, even though the drilling depth is constant, the distance from the base point has to be calculated and the drill-workpiece distance specified accordingly. Furthermore, although scribing, punching and drilling are more often than not required in the same stage of processing and positioning along the X and Y axes is indispensable for every such operation, there is no machine available at present that can carry out all these operations by itself. A conventional automatic machining system incorporating an NC drilling unit of the aforementioned type is seen in "Planning for numerical control" of MACHINERY and production engineering, pp. 521-529 by Earl J. Donelan, Sept. 8, 1965.